1. Field of the Invention
The present invention relates to a process for preparing a polymer composition containing a physiologically active substance. More particularly, the present invention relates to a process for preparing a polymer composition containing a physiologically active substance and having a property of releasing the substance at a controlled rate.
2. Prior Art
The present inventors have previously invented a process for preparing a polymer composition having a property of releasing a physiologically active substance at a controlled rate which comprises contacting a polymerizable monomer and the physiologically active substance and irradiating them with light or an ionizing radiation to polymerize the monomer (Japanese Patent Application No. 27,109/78, U.S. Ser. No. 018,617) and, further, on the basis of this invention, have accomplished a series of inventions of a process for preparing a polymer composition having the same property which comprises dropping or injecting a mixture of one or more monomers vitrificable at low temperatures containing a high molecular weight substance and the physiologically active substance into a medium to make the mixture into a shape of spherical structure and irradiating it with light or an inoizing radiation (Japanese Patent Application No. 51,239/78, U.S. Ser. No. 018,617), a process for preparing a polymer composition in which the elution rate of the physiologically active substance is controlled by pH which comprises irradiating a uniform mixture of a polymer soluble in a pH within a certain range, a polymerizable monomer and the physiologically active substance with light or an ionizing radiation to polymerize the monomer (Japanese Patent Application No. 105,306/78, U.S. Ser. No. 18,617), a process for preparing a polymer composition having the same property which comprises mixing a polymerizable monomer and physiologically active substance in the presence or absence of crystallizable substance, adding an adsorbent thereto and irradiating it with light or an ionizing radiation (Japanese Patent Application No. 106,097/78, U.S. Ser. No. 18,617), and a process for preparing a polymer composition containing an antitumour agent and having a property of releasing it at a controlled rate which comprises mixing a polymerizable monomer with two or more antitumour agents, or one or more antitumour agents and a substance promoting antitumour effect and irradiating the mixture with light or an ionizing radiation (Japanese Patent Application No. 146,411/78, U.S. Ser. No. 095,496). However, a physiologically active substance is generally broken or decomposed by the action of radiation and thereby its activity lowers. In order to restrain the lowering of activity, in the processes of these inventions, the irradiation has been performed at ordinary temperatures or in a lower temperature domain as below 0.degree. C. Therefore, the monomer to be used had to be a monomer polymerizable at low temperature.